Global child vaccination needs a data boost

Vaccinating the world's children saves millions of lives, but the system of monitoring such efforts needs a revamp, says Seth Berkley of the GAVI Alliance

HOW many vaccines do you think it takes to fully immunise a child? One? Three? Perhaps five? By the World Health Organization's reckoning, that number is 11 – that's 11 key vaccines every child should have to protect them from a range of devastating diseases. So why then are we only using three to measure immunisation coverage? By doing so, we are not only giving ourselves a skewed perspective of the state of global childhood immunisation, but we are also in danger of thinking it's job done, when we still have far to go.

At first glance, it appears that we have almost won this particular health battle, with the proportion of the world's children receiving routine vaccinations climbing steadily from 73 per cent a decade ago to about 83 per cent today. But that's only when you measure the uptake of three basic childhood vaccines, completed on the third dose of diphtheria-tetanus-pertussis (DTP). When you include all of the 11 that the WHO says every child should have, a very different picture emerges. Less than 5 per cent of the world's children are fully immunised when you add BCG (for tuberculosis), measles, rubella, polio, hepatitis B (hep B), Haemophilus influenzae type B (Hib), pneumococcal and rotavirus vaccines.

Such a discrepancy exists because for the last three decades the global health community – governments, international organisations and aid agencies – have used just one or two "tracer" vaccines to measure immunisation coverage, usually the third dose of DTP or sometimes the first dose of measles. In the past, these worked because they not only allowed us to gauge the reach of immunisation programmes, but also, in the case of DTP, it showed the strength of countries' health systems because it requires three contacts with those systems.

These indicators are now antiquated, limited and wholly misleading. Only a small percentage of countries still use traditional DTP, the majority having switched to modern combination vaccines like the 5-in-1 pentavalent vaccine, which combines DTP with hep B and Hib. So in fact a large proportion of the 83 per cent are actually getting five vaccines. Also, in terms of impact on reducing child mortality, DTP no longer provides an accurate picture. With the development and availability of pneumococcal and rotavirus vaccines, we can now protect children from the two biggest childhood killers, pneumonia and diarrhoea, which account for 29 per cent of all deaths in under-5s each year, or two million lives.

So by continuing to use DTP as a measure of coverage there is a danger that we become complacent. For, even though the number of fully immunised children is on the rise, based on current projections, by 2030 it will still only have risen to the point that barely more than half of the world's children will be receiving all 11 vaccines.

If you just take the world's 73 poorest nations – those that my organisation, the GAVI Alliance, supports, and where disease risks are highest – this 2030 figure is still only forecast to be about 70 per cent. The figure is higher there because use of all 11 vaccines is more likely than in richer nations where, for example, TB shots are no longer deemed necessary for all.

Using the new measure would almost certainly help improve the situation, but it's not the only vaccine metric in need of a revamp. The value we place on immunisation is also failing to capture the big picture.

Typically, when we talk about the need to vaccinate children it is in terms of saving lives and preventing illness. While it does this, in the last few years we have seen a growing body of evidence suggesting that this is only part of the story; that the full benefits extend beyond protecting health and saving lives, and reach well into a child's later life.

By avoiding multiple illnesses, vaccinated infants can grow into healthier children who are able to attend school more. And they don't just do better at school. Through the prevention of damage that can be caused by infectious diseases, they also appear to benefit in terms of cognitive development. All this helps the family and the wider economy, with parents able to work instead of caring for a sick child, generating more income and increasing their spending power.

That is not to say that vaccines alone are the solution to fighting poverty, but rather that their role in removing some of the causes of poverty is vastly underestimated. As a public-health intervention, immunisation is already widely seen as one of public health's "best buys", but by measuring the effectiveness in terms of lives saved, it seems likely that we are undervaluing the benefits and the return on investment they offer.

More research is needed to better understand and quantify the relationship between full immunisation coverage and the range of benefits for individuals, households, communities and countries. What is clear, however, is that if more children got all 11 vaccines, the benefits would be amplified and the impact on health and poverty reduction would be profound.

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